"Wait a minute, I don't want to say that," the Nebraska Democrat said. "Those of us who are appalled by it, those of us who are angered by it, we need to stop it."

The target of Saturday's attack, Rep. Gabrielle Giffords (D-Ariz.), was shot in the head and is in critical condition. Six are dead, including a federal judge and a child, and at least 14 more are wounded. While cause and effect may never be made clear in Arizona's horror, the political context of the bloodshed is a level of heightened partisanship and anti-government rhetoric that in recent years has devolved from harsh to openly violent, if only in metaphor. Palin's website famously featured a "hit list" of Democrats to be defeated in 2010, including Giffords, and those on the list were highlighted with rifle-scope cross hairs. "Don't retreat," Palin urged visitors to the site, "instead — RELOAD."

The 2008 presidential campaign featured an undercurrent of violence that alarmed the Secret Service. After Barack Obama won the presidency, some people attended his events carrying guns. The town hall meetings lawmakers held in 2009 to discuss health care often flared into angry protests, prompting members to speak about fears of violence and vandalism.

The examples of inflammatory discourse abound, from gas lines being cut at the home of then-Rep. Tom Perriello's (D-Va.) brother when his address was posted on the Internet, to Rep. Michele Bachmann (R-Minn.) asking her supporters to get "armed and dangerous." Republican Sharron Angle referred to "Second Amendment remedies" as she campaigned to unseat Senate Majority Leader Harry Reid (D) in Nevada.

"The more people do that, they've got to realize there's consequences to that action," Giffords herself had said about the Palin "hit list."

Giffords' 2010 rival held an event offering supporters a chance to shoot an M16 and "help remove Gabrielle Giffords from office."

Perriello told Roll Call he has less of a problem with Palin's target list (he was on it) than with the subtle "dehumanization" of political enemies that can spark violence. "To a crazed mind or a mind that might be prone to violence," name-calling can feed vitriol more than any campaign flier using cross hairs, he said.

"The [campaign] language has been very strong, and, it seems to me, inflammatory," former Attorney General Nicholas Katzenbach told Roll Call on Sunday.

Katzenbach, who served under President Lyndon B. Johnson and is best remembered for his role confronting Gov. George Wallace at the University of Alabama in 1963, said he fears long-term consequences: "If they denounce you as some kind of evil person it's going to get harder and harder to attract people into politics."

U.S. District Judge John Roll, among those slain in Tucson, had been the target of death threats after a 2009 ruling that a lawsuit by illegal immigrants against an Arizona rancher could go forward. The Arizona Republic reported the judge got more than 200 phone calls after talk-radio hosts criticized his ruling, prompting authorities to give Roll's family protection.

Some drew parallels between Saturday's events and the bombing of the Oklahoma City federal building during a period of heightened anti-government sentiment.

President Bill Clinton sounded a note of caution in a New York Times opinion piece on the 15-year anniversary of the bombing last April, writing, "We are again dealing with difficulties in a contentious, partisan time."

"As we exercise the right to advocate our views, and as we animate our supporters, we must all assume responsibility for our words and actions before they enter a vast echo chamber and reach those both serious and delirious, connected and unhinged," Clinton wrote.

Democrats, of course, have contributed, too. In 2004, the Democratic Leadership Council posted an election map, with a graphic of the country labeled "Behind enemy lines" that featured bull's-eye targets over nine states. They also posted links to stories mentioning Obama's 2008 campaign comment, "If they bring a knife to the fight, we bring a gun."

In a sign of how difficult it can be to escape the cycle of escalated rhetoric, the news out of Arizona prompted harsh attacks against Palin. It took only a few minutes for partisans on the Internet to remember that Giffords' 8th district was among those on Palin's list, and for bloggers to screengrab the rifle-scope image and spread it around. A Palin aide said in a radio interview that it was "obscene" to suggest a link between Palin and the shooting, but Internet commenters flooded Palin's Facebook page, posting vicious complaints about her that were instantly being erased.

"Mission accomplished, Sarah Palin," Daily Kos founder Markos Moulitsas tweeted less than an hour after the nation learned of the bloodshed in Arizona.

But even as people cautioned that cooler heads should prevail, the opposite happened. Instead of taking a step back to evaluate discourse in America, the tone got even hotter.

A left-leaning political activist tweeted directly at Palin that he thinks she could never run for president. He wrote, "You gotta walk into EVERY coffee shop in Iowa. With Christina Taylor Green's blood on your hands," referring to the child killed at Giffords' event.

Tea party leaders decried the shootings in Arizona and pushed back against any guilt-by-association.But after the group was "attacked" for the shootings, Judson Phillips of Tea Party Nation wrote this weekend that the era of agreeing to disagree was over.

"[T]he aftermath of today's shooting is the official obituary for political civility in this country," he wrote. "The left has simply gone to far. There can be no civil discourse with people as crazy as those on the left are. What that says for the future of this country is tragic."

Kerrey told Roll Call that "hyperbolic, almost dangerous rhetoric" is nothing new in politics. The problem, he said, is comments are amplified a thousandfold by the Internet and social media. "There may not be a direct connection, but you encourage people who lack the mental stability about what they should or shouldn't do," he said.&#8233;Former Rep. Connie Morella (R-Md.) told Roll Call she believes "irresponsible sloganeering" has driven the parties further apart. Morella, now with American University, said in politics today, "there is right and there is wrong and there is no in-between way to work together."

Like Kerrey, politicians and journalists seemed to be taking a cue to cease with inflammatory language.Assistant Leader James Clyburn (D-S.C.) summed up political consensus on "Fox News Sunday": "Words do have consequences."

Correction: Jan. 10, 2011

The article&nbsp;misstated the anniversary of the Oklahoma City bombing on which President Bill Clinton wrote a New York Times opinion piece. It was the 15-year anniversary.